Mental illness constitutes one of the world's most critical and social health problems. It affects more human lives and wastes more human resources than any other disabling condition. The ILO’s activities promote the inclusion of persons with physical, psychiatric and intellectual disabilities into mainstream training and employment structures. The ILO’s primary goals regarding disability are to prepare and empower people with disabilities to pursue their employment goals and facilitate access to work and job opportunities in open labour markets, while sensitising policy makers, trade unions and employers to these issues. The ILO's mandate on disability issues is specified in the ILO Convention 159 (1983) on vocational rehabilitation and employment. No. 159 defines a disabled person as an individual whose prospects of securing, retaining, and advancing in suitable employment are substantially reduced as a result of a duly recognised physical or mental impairment. The Convention established the principle of equal treatment and employment for workers with disabilities.